A Spectroscopic Study of V617 Sagittarii

(1) Divisão de Astrofísica, Instituto Nacional de Pesquisas Espaciais,
CP 515, 12201-970 São José dos Campos, Brazil
(2) Laboratório Nacional de Astrofísica, CP 21, BR-37500-000 Itajubá - MG, Brazil

Abstract:

We present the results of an analysis of time-resolved spectroscopy of V617 Sgr, the Wolf-Rayet star WR 109, in the Hbeta and HeII lambda 4686 region. Radial velocity curves were obtained confirming the orbital period of 4.97 h found from photometric observations. These curves indicate that the superior conjunction of the line forming region occurs close to the primary eclipse. Constraints on the stellar masses in this peculiar binary are derived from the emission lines. The orbital behavior of the emission line profiles is analyzed in detail. A Doppler tomography study of the Hbeta and HeII lambda 4686 lines is performed aiming to estimate the locus of line formation in the system. The observations may suggest the presence of an optically thick wind. An extended emission region consistent with a hot spot and free falling gas is also inferred from our analysis.

The observed characteristics, as strong intensity of HeII lambda 4686 (HeII/Hbeta flux ratio about 2.8) and the presence of emission lines of highly ionized elements like NV and OVI, are not usually seen in normal cataclysmic variables and, in this respect, V617 Sgr is quite similar to the star V Sge.

binaries:cataclysmic variables, stars:individual (V617 Sgr), stars: mass loss, Wolf-Rayet